It is all about advanced metallurgy with replicas made today (both lever rifles and SA revolvers). The 44-40 was introduced in 1873. It was a popular duel carry cartridge as both rifles and revolvers were chambered in it. Pressures in the 44-40 at 16,000 psi were most likely held for many of the revolvers used in the day. Having a rifle in the same cartridge as your revolver was a real nice attribute and the 44-40 was extremely popular for that use. Even so, I'm guessing the rifles of the day could of handled a bit more pressure than the revolvers of the day.
